Simulated plant-derived exudate pulses promote maize phosphorus uptake by recruiting specific rhizosphere microbial communities and shaping root metabolites

Abstract

Exudates are known to drive rhizosphere interactions, yet their distinct roles in enhancing plant phosphorus (P) uptake through microbial recruitment and metabolic regulation remain unclear. In this study, we investigated whether these exudates could stimulate soil P mobilization and improve the P uptake of maize. In brief, we added two concentrations of six exudates once every five days, naturally found in plant roots or microbes and released into the soil during maize growth. The results showed that adding exudate substances significantly increased the biomass and P uptake of maize. This enhancement was linked to alterations in root metabolism and modified plant-microbe interactions in the rhizosphere. Specifically, exudate additions increased the relative abundance of Gaiellales (from 2.7 % to 4.7 %), which positively correlated with shoot P content and soil phosphatase activity, suggesting a potential role in P mobilization, particularly when plant-derived exudates were introduced. Furthermore, a random forest model identified key exudate-affected metabolites (Met2 and Met25) that correlated significantly with maize growth and P uptake. Notably, the microbial community showed a stronger correlation with maize P uptake than root metabolism. The findings indicate that plant-derived exudates are more effective than microbial-derived exudates in improving plant P uptake. This research will provide a theoretical support for utilizing plant exudates to improve the soil phosphates bioavailability.